DESCRIPTION (Adapted from the application) This core in the previous funded period was the Immunoassay Core. The objectives of this core is to provide the investigators 1. with convenient and accurate RIA, ELISA, or Western blot analyses; 2. the opportunity to generate new antibodies or immunoassays that are not commercially available; 3. the option of rigorously evaluating the specificity of any immunoassay with a battery of supplementary biochemical analyses, including HPLC characterization and or Western blotting of antigen-containing extracts, and 4. the capability to use antigenic determinants to generate pure populations of cells for direct analysis, or for further study in conjunction with the tissue culture capabilities of the Advanced Cell Technologies (ACT) core.